The present invention relates to a system and method for absorbing grease. In particular, the present invention relates to a system and method for absorbing and containing the grease vaporized or generated by cooking food and discharged from a rooftop exhaust vent.
Cooking food, in particular meat and meat products, can vaporize and/or generate various types of fat, oil and grease (referred to collectively as grease). Restaurants and fast food outlets can produce significant amounts of airborne and vaporized grease which is carried away from the vicinity of the stove, cooking range, grill or fryer by the kitchen exhaust system. The effluent gas and combustion products comprise the exhaust which is conducted by ducts to a rooftop exhaust vent or outlet where it is released into the atmosphere. The grease discharged with the exhaust from the exhaust vent can condense from the effluent exhaust gas and drip onto the rooftop adjacent to the exhaust vent. The vent can comprise a fan such as an upblast or blower type fan.
Deposits of grease on the roof can stain, damage and corrode the roof, appear unsightly, create unpleasant odors and prove a substrate for microbial germination. Additionally, accumulations of grease on the rooftop can create both a fire hazard due to the highly flammable nature of the grease and a safety hazard for those working on the roof due to the slippery nature of the grease. Furthermore, condensations of the grease on the exhaust vent at or near the position of the effluent exit from the exhaust vent can damage the vent and present a fire hazard.
Rooftop silica sand (such as heavy, crushed pumice rock) filled sand boxes for absorbing cooking grease released from restaurant rooftop vent effluent gases are known as disclosed by U.S. Pat. No. 4,887,588. Unfortunately, an absorbent silica sand or powder cannot be enclosed and used within an easily installed, removed and disposed of bag because making pores in the bag material small enough to retain the sand granules prevents the grease from permeating the bag and reaching the absorbent sand within the bag. And, as is well known, loose or unbagged sand is easily scattered. Additionally, a sand box type product being placed around the bottom of the exhaust vent cannot prevent the accumulation of grease in the vent or on the interior of the vent or fan.
Also known is the use of an open mesh fabric container enclosing polymeric particles for the absorption of cooking grease near rooftop exhaust ducts, as discussed by U.S. Pat. No. 4,923,725. Organic based polymeric products can be expensive to produce and can melt if placed on or in the exhaust vent, resulting in a dramatic reduction of surface area and concomitant loss of absorbency.
Both sand and polymeric particles can suffer adverse effects on their absorbency function from exposure to the elements, necessitating multilayer, difficult to access mechanical enclosures or plates which shelter the sand or particles while still permitting access by the grease to be absorbed. Sand or other granular material is particularly difficult to retain in a desired location and cannot be bagged in a material significantly permeable to high viscosity cooking grease.
What is needed therefore is a rooftop grease containment system which can absorb the grease at multiple locations in and around the exhaust vent where the system is economical, easy to maintain with no requirement for any tools or equipment and can be quickly installed and removed.